I Have A New Toy............. URS4 Avant

[newsh]

Are all the ground wires intact to the inlet manifold bolts?
Engine earth straps?
Could it be running out of fuel? As in fuel pump not keeping up?

[newsh]

Debris in the tank?

[Kieron20V]

The ECU is actually cutting the fuel pump relay, it's not that it's running out of fuel, it's turning it off. This is exactly what was happening to me Sean, I thought the cam sensor had sorted it.

Sent from my Nexus 6P using Tapatalk

[Sleeper_Avant]

It only does it when it is hot, I'm going back to the crank sensor with a scope today and having someone drive it from cold.

Off work for next 2 weeks so I better be right or I wine be using it on 3rd March when my ban ends

Come on girl, show me some love please

[prj]

The ECU will cut and enable the fuel pump based on the engine speed sensor.
It has to show more than 13 rpm for the relay to be activated.

If you have that engine speed sensor code with engine running (not just ignition on) then you have a problem with the sensor. Try replacing it.

Also, looks like the O2 sensor is shot, that would also explain the sooty looking plugs.

[Sleeper_Avant]

I had the oscilloscope out most of the day,
Waveforms taken from cam, reference and rpm sensors,
No interference or correlation problems from cam or crank/reference sensors.


I have more but will post once photobucked uploads them....

Also in 2nd it revved right round past 7500rpm twice.

Most of the time it just won't rev past 4000/4500.

Hasn't cut the fuel relay, but I have disconnected both knock sensors .

Also today I have made external relay mod with battery live feed and switched, made no difference.

I am going in to work next week to sort this while on holiday as it's doing my nut in!

I am a Master Technician by trade and can't fix my own fecking car!!!!

So, replaced this week:

New cam and RPM sensors,
Fresh fuel,
New plugs
Oil and filter
Coilpack and loom upgrade
ALL inputs look fine and problem occurs with every input disconnected except rpm sensor.
Fuel pump relay has been made to ensure pump has maximum current from battery
Engine earths removed , cleaned, greased and refitted

Next on the list:

Check fuel pressure,
Check for fuel line damage/kinks
Check fuel return line as this would cause excessive pressure rich running and poor running.

PRJ,
Even holding revs at 2500 with no load, engine stutters, not missfire and black smoke visable from tailpipe
O2 sensor is new Bosch item just like cam and crank sensors.

Is it possible software has gone bad?.I don't know if it could be but no more evidence to look at now really.

Ecu I have had open, everything in place and no dry solder joints visable.

I just wish it was something obvious!!

On the odd occasion it is perfect and will rev hard past 7500, not hot rev limmier and backed off.

I am getting new laptop tomorrow and vagcom ready for Monday, hopefully live data will help me more.

I am diagnosing blind right now.

Any help greatly appreciated.

[prj]

Software can't go bad.
But the ECU can.

If the relay clicks it's losing sync/rpm signal for some reason. Make sure your coil adapter loom has a proper ground to the engine (at the cam cover).

Also, try another ECU. Swap the chip on the upper board over, that'll allow it to have more or less correct fuel/ign. It will be a bit richer without the R201 mod done, but it should still run alright.

[Sleeper_Avant]

I did suspect that was the case,

I will do a pin out check on the new loom, earth was very good, checked voltage drop and all good.

Also, still does this with the old coils fitted,

Imagine ramping up the resistance on a rolling road, this is what we have here.

Will also check wiring just in case ECU is not receiveing signals etc.

Thanking very much for the help

[twoqu]

Does this car have Dmitri's SW? If so can the launch control cause any of these issues?

[prj]

I'd just try a known working ECU tbh.
From what you described it seems like the ECU is bad.

Either that or there is massive EMI coming in from somewhere.

[prj]

Does this car have Dmitri's SW? If so can the launch control cause any of these issues?

No idea if it does, but easy to tell on VCDS.

Launch control can not cause any of this.
If it is not a MAFless car the launch control limiter is simply an alternate limiter using the stock method, which gets activated whenever the car is not moving.

Basically changes the stock limiter to X rpm from the normal 7200 if you are stationary - all there is to it. Since all values are hardcoded it can not change itself in any way either.

[twoqu]

It's just the 5K rev limit that got me thinking!
Reading back through the posts seems to imply it has launch control and as far as I am aware you might have been the only person offering that.

[Sleeper_Avant]

PRJ,
Car does have your software and 5000rpm launch control.

Problem only present when under load,

It will happily sit on the 5000rpm limiter in neutral all day long and when driving in gear with speed sensor unplugged it will rev to 5000 limmiter on most occasions

Very odd.

I am not blaming software, just wondered if that was a variable here.

I will check all wiring and fuel pump variables and scope readings at the ECU plug incase wiring is no good.

Also posted wanted and for ECU to buy or borrow.

Again, thank you for the help

[twoqu]

I was thinking that whatever activates the launch control (clutch switch?) is stuck or something!
Before blaming the ecu, take a closer look at the innards or at least post some pics of the components. If its modified it should have a diffferent map sensor. Again if the chips have been reprogrammed the original silver stickers would have been replaced. Might even have the vendors ID on them.
Does your diagnostic sw ID the sw version of the ecu? Ignore what it says on the case.

[Sleeper_Avant]

I will pull the ECU out again on Monday, it has non standard map sensor and chipset,

I saw no damage to any solder joints or wiring at the plug etc

Hopefully vag-com may shed some more light on something